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Analog Devices Inc. LTC1735CS-1#TRPBF
- Part No.:
- LTC1735CS-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1735CS-1#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,521
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Product details
Overview
LTC1735CS-1 from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller optimized for CPU core power delivery in mobile computing systems. It delivers 0.8V to 7V output with ±1% accuracy, supports 3.5V–30V input, operates up to 500kHz, and features OPTI-LOOP™ compensation and programmable current sensing for Intel Mobile CPU-compliant power-good signaling.
For engineers reviewing the LTC1735CS-1 datasheet, LTC1735CS-1 pinout, LTC1735CS-1 application, or LTC1735CS-1 equivalent, key selection criteria include its dual N-channel MOSFET synchronous drive capability, 99% duty cycle dropout operation, Burst Mode™ efficiency at light load, remote voltage sense, and Intel SpeedStep™-compatible dynamic voltage scaling support.
Technical Context
The LTC1735CS-1 implements a constant-frequency, current-mode control architecture with an internal transconductance error amplifier (gm = 1.3 mmho) and dual current comparators for peak-current limiting and foldback protection. Its OPTI-LOOP™ compensation minimizes required output capacitance by adapting loop response to wide ESR/capacitance variations.
It integrates a 5.2V internal LDO (INTVCC) with switchover to EXTVCC ≥4.7V, supports external synchronization via PGOOD pin (0.9–1.3× fOSC), and includes dedicated gate drivers (TG/BG) with 3A peak current, 50–90ns transition times, and bootstrap capacitor recharge logic for dropout operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 0.8V to 7V - Programmable via external resistor divider; enables dynamic VOUT scaling for CPU DVFS. |
| Input Voltage Range | 3.5V to 30V (36V abs max) - Supports wide-input industrial and notebook battery rails. |
| Feedback Accuracy | ±1% at VOSENSE - Ensures tight regulation across temperature and line/load conditions per Intel Mobile CPU spec. |
| Power-Good Window | ±7.5% of set VOUT - Matches Intel Mobile CPU power-good timing requirements for safe CPU boot and state transitions. |
| Max Duty Cycle | 99.4% - Enables ultra-low dropout operation when VIN approaches VOUT, critical for battery-end-of-life scenarios. |
| Quiescent Current | 450µA normal mode; <25µA shutdown - Minimizes standby power loss in portable systems. |
| Oscillator Frequency | 265–335kHz (COSC = 47pF); synchronizable up to 500kHz - Balances efficiency vs. size; external sync eliminates EMI beat frequencies. |
| Current Sense Threshold | 60–85mV - Sets peak inductor current limit; user-programmable via RSENSE for precise overcurrent protection. |
Pinout & Package
The LTC1735CS-1 is housed in a 16-lead narrow SO package (SO-16), thermally enhanced for high-current DC/DC controller applications. Pin assignments are validated per Linear Technology's official datasheet revision.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COSC (1) | Oscillator Timing Input | Connects to external capacitor setting switching frequency; enables precise frequency tuning and synchronization. |
| RUN/SS (2) | Soft-Start & Enable Control | Capacitor-based soft-start ramp; <1.5V disables controller; discharge initiates latchoff during sustained overcurrent. |
| ITH (3) | Error Amplifier Output | Controls peak inductor current; voltage range 0–2.4V directly sets current limit threshold. |
| PGOOD (4) | Open-Drain Status & Sync Input | Indicates ±7.5% VOUT regulation; external clock input forces sync mode and disables Burst Mode™. |
| SENSE– (5), SENSE+ (6) | Differential Current Sense Inputs | Monitor voltage across RSENSE; built-in offset enables accurate current measurement independent of common-mode voltage. |
| VOSENSE (7) | Feedback Voltage Input | Receives scaled output voltage; referenced to 0.8V internal bandgap for ±1% regulation accuracy. |
| SGND (8) | Small-Signal Ground | Reference point for COSC, feedback divider, and compensation network; must be single-point tied to PGND. |
| EXTVCC (9) | External Bias Supply Input | Switches internal LDO off when >4.7V applied; allows efficient self-biasing from converter output rail. |
| PGND (10) | Power Ground | Return path for bottom MOSFET source, input capacitor, and Schottky diode anode; separates high-current paths from SGND. |
| BG (11) | Bottom Gate Driver Output | Drives N-channel MOSFET source-to-ground; swing from 0V to INTVCC (5.2V) with 3A peak capability. |
| INTVCC (12) | Internal Regulator Output | 5.2V LDO output powering control circuitry and gate drivers; requires 1µF ceramic + 4.7µF tantalum decoupling. |
| VIN (13) | Main Input Supply | Primary power input (3.5–30V); must be closely decoupled to PGND to suppress high di/dt noise. |
| SW (14) | Switch Node | Connection to inductor and bootstrap capacitor; swings from –0.4V (Schottky drop) to VIN during operation. |
| BOOST (15) | Bootstrap Supply Return | Return node for floating bootstrap capacitor; voltage swing = INTVCC superimposed on SW node. |
| TG (16) | Top Gate Driver Output | Drives N-channel MOSFET gate referenced to SW node; floating driver with 3A peak current capability. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP™ Compensation | Adapts loop bandwidth to output capacitor ESR and value-eliminates need for iterative stability tuning across production batches. |
| Programmable Current Limit | Set via RSENSE with 60–85mV threshold-enables precise overcurrent protection matched to MOSFET SOA and PCB trace limits. |
| 99% Duty Cycle Dropout Operation | Maintains regulation down to VIN − VOUT ≈ 100mV-extends usable battery life in portable systems operating near end-of-discharge. |
| Remote Output Voltage Sense (VOSENSE) | Compensates for IR drop in high-current PCB traces-ensures ±1% accuracy at CPU load point, not at converter output. |
| Logic-Controlled Micropower Shutdown | IQ < 25µA in shutdown-reduces system standby power consumption without requiring external enable sequencing. |
| Intel Mobile CPU Power-Good Compliance | ±7.5% window comparator with fast response-meets Intel SpeedStep™-enabled processor boot, sleep, and state-transition timing requirements. |
Applications
| Mobile CPU Core Power | Notebook System Power |
|---|---|
Use Scenario: Dynamic voltage/frequency scaling (DVFS) for Intel Pentium® III processors with SpeedStep™ technology in ultraportable notebooks. IC Role / Device Role / Timing Role: Primary CPU core supply controller managing real-time VOUT transitions between 1.35V and 1.60V under OS-directed load changes. Use Value: Enables >30% reduction in CPU active power while maintaining full performance headroom during burst loads via fast transient response and OPTI-LOOP™. | Use Scenario: Main 1.6V/12A system rail generation from 4.5–24V battery input in clamshell-form-factor notebooks. IC Role / Device Role / Timing Role: High-efficiency synchronous buck controller driving dual FDS6680A MOSFETs with remote sense to CPU VRM. Use Value: Delivers >90% efficiency across 10mA–12A load range using Burst Mode™ at light load and continuous sync mode at full load. |
| Wireless Modem Power | Industrial Embedded CPU Supply |
Use Scenario: Compact 3.3V/3A power rail for LTE/Wi-Fi baseband processors in space-constrained cellular handsets. IC Role / Device Role / Timing Role: Step-down controller interfacing with external 3.3V LDO post-regulator and enabling fast PGOOD assertion for modem boot sequence. Use Value: Meets stringent RF noise requirements via selectable sync mode and low-noise constant-frequency operation during data transmission. | Use Scenario: Reliable 1.2V/8A core supply for ARM Cortex-A series SoCs in fanless industrial gateways operating from 12–24V DC input. IC Role / Device Role / Timing Role: Robust controller with latched short-circuit shutdown and thermal derating support for unattended 24/7 operation. Use Value: Ensures system uptime via foldback current limiting and automatic latchoff recovery-no manual reset required after fault clearance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2315DJ-LF-Z | Integrated power stage (MOSFETs internal); fixed 500kHz fSW; no EXTVCC option; ±2% VREF accuracy. | Lower BOM count for <5A designs; lacks remote sense and Intel PGOOD compliance; unsuitable for CPU DVFS. | Select MP2315 for cost-sensitive, medium-current applications where integrated FETs simplify layout but programmability is secondary. |
| TPS54620RGYR | Integrated FETs; 2.95–17V input; 0.6–7V output; 4.5–20V VDD bias; no Burst Mode™; uses D-CAP2 control. | Higher integration reduces footprint; lacks OPTI-LOOP™ adaptability and Intel PGOOD window; optimized for server VRMs, not mobile CPUs. | Choose TPS54620 for high-density, fixed-input industrial supplies where fast transient response matters more than light-load efficiency or CPU-specific compliance. |
Compared with MP2315DJ-LF-Z and TPS54620RGYR, the LTC1735CS-1 uniquely combines external MOSFET drive flexibility, OPTI-LOOP™ adaptive compensation, Intel-compliant PGOOD, and Burst Mode™-making it the only viable choice for high-reliability, dynamically scaled CPU core supplies in mobile platforms.
Availability
LTC1735CS-1 is available at Aetrix Electronics and suitable for notebook computers, wireless modems, and industrial embedded CPU power systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC1735CS-1 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC1735CS-1 belongs to ADI's legacy Linear Technology Power Management product line, specifically engineered for high-efficiency, dynamically scalable CPU core power in mobile and embedded computing platforms.
FAQ
What is the maximum input voltage rating for the LTC1735CS-1?
The LTC1735CS-1 has an absolute maximum input voltage rating of 36V at the VIN pin. Continuous operation is specified from 3.5V to 30V. Exceeding 36V risks permanent damage to internal circuitry, including the gate drivers and INTVCC regulator. The device includes undervoltage lockout (UVLO) that disables operation below 3.5V to prevent erratic behavior during brownout conditions.
Does the LTC1735CS-1 support remote voltage sensing, and how is it implemented?
Yes, the LTC1735CS-1 supports remote voltage sensing via the VOSENSE pin (Pin 7). This pin receives feedback from an external resistive divider placed directly at the CPU load point-not at the converter output-to compensate for IR drop in high-current PCB traces. The internal 0.8V reference compares against VOSENSE, enabling ±1% regulation accuracy at the point of load, which is essential for modern low-voltage, high-current CPU cores.
How does Burst Mode™ operation improve light-load efficiency in the LTC1735CS-1?
Burst Mode™ operation in the LTC1735CS-1 disables both top and bottom MOSFETs when the ITH voltage drops below 0.5V, allowing the output capacitor to supply load current until regulation error triggers resumption. This eliminates switching losses and gate drive power at light loads, achieving >85% efficiency at 10mA output-significantly higher than forced continuous mode. Burst Mode™ is enabled by pulling PGOOD above 0.8V, typically via a resistor to INTVCC.
Can the LTC1735CS-1 be synchronized to an external clock, and what are the constraints?
Yes, the LTC1735CS-1 can be synchronized to an external clock applied to the PGOOD pin via a series resistor. The internal oscillator locks to frequencies between 90% and 130% of its nominal fOSC (set by COSC). Clock high must exceed 1.3V for ≥0.3µs and low must be <0.3V for ≥0.3µs. Synchronization disables Burst Mode™ but enables constant-frequency, low-noise operation ideal for EMI-sensitive applications like wireless modems.
What protection features does the LTC1735CS-1 include for overcurrent and short-circuit conditions?
The LTC1735CS-1 includes foldback current limiting (activated when VOSENSE < 0.6V), internal current foldback that reduces peak inductor current to ~25% of maximum, output overvoltage crowbar (shuts off top FET, turns on bottom FET), and a latched short-circuit shutdown timer triggered via RUN/SS capacitor discharge. The latchoff can be defeated by injecting >5µA into RUN/SS, providing flexible fault recovery strategies for mission-critical embedded systems.
LTC1735CS-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 3.5V ~ 30V
- Frequency - Switching:
- 300kHz
- Duty Cycle (Max):
- 99.4%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Power Good, Soft Start
- Operating Temperature:
- 0°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
LTC1735CS-1#TRPBF FAQ
1.How can I place an order for LTC1735CS-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1735CS-1#TRPBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LTC1735CS-1#TRPBF reliable?
The price and inventory of LTC1735CS-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1735CS-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1735CS-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1735CS-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1735CS-1#TRPBF?
LTC1735CS-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1735CS-1#TRPBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LTC1735CS-1#TRPBF?
For technical support, including LTC1735CS-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1735CS-1#TRPBF requirements.
6.How does Aetrix verify that LTC1735CS-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1735CS-1#TRPBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LTC1735CS-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1735CS-1#TRPBF?
All LTC1735CS-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1735CS-1#TRPBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LTC1735CS-1#TRPBF part is unused and in its original packaging.
Return procedure for LTC1735CS-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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